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Type 1 diabetes, also called juvenile diabetes, and celiac disease, also called celiac sprue, are both autoimmune diseases, a class of diseases in which the body's immune system attacks itself. In type 1 diabetes, the immune system destroys the cells in the pancreas that secrete insulin, a hormone vital for regulation blood sugar. In celiac disease, a protein called gluten found in certain grains, especially wheat, triggers the immune system to attack the small intestine. (Type 1 diabetes is distinct from type 2 diabetes, also called adult-onset diabetes, which has different causes.)
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The Connection Between Celiac Disease and Type 1 Diabetes
Research has shown a clinical link between the two conditions, with celiac disease five to ten times more likely to occur in a patient with type 1 diabetes than in a person without it (Lite, 2008). Since both diseases are known to have genetic factors in their etiology, it stands to reason that the genes for them may be linked in some way. Some previous studies, however, have indicated that this connection may not mean that the two diseases are caused by the same genes (see, for example, Naluai et al., 2000, and Bilbao et al., 2006).
Now a new study (Smyth et al., 2008) has shown evidence that type 1 diabetes and celiac disease may be caused by the same genes after all. The study, which involved patients with both diseases and a control group, found up to seven chromosomal regions related to both celiac disease and type 1 diabetes.
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Can Gluten Trigger Type 1 Diabetes?
Celiac disease lurks harmlessly in a patient who does not consume gluten. This protein is the trigger for the immune system to attack the small intestine, where it damages the villi and causes problems including malabsorption of nutrients and gastrointestinal complaints. Fortunately, the removal of gluten from the diet ends the immune system's rampage, and the small intestine heals, leaving the patient again symptom free.
This is not the case with type 1 diabetes. Once the insulin-producing cells in the pancreas are destroyed, they do not regenerate, and the patient remains unable to produce insulin for the rest of his or her life.
If type 1 diabetes and celiac disease not only share a genetic link, but are actually caused by the same exact genes, does this mean that dietary gluten is the trigger for the immune system attacks that cause type 1 diabetes? This conclusion is a possibility, but the research has not yet shown whether this is the case. Experts point out that it would be "premature" to assume that gluten can cause type 1 diabetes in genetically susceptible individuals (Lite, 2008). Further research into the etiology of type 1 diabetes is necessary before definite conclusions can be made about its potential environmental triggers.
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- Bilbao, J. R., et al. October 2006. "Conserved extended haplotypes discriminate HLA-DR3-homozygous Basque patients with type 1 diabetes mellitus and celiac disease." Genes and Immunity 7:7 (550-554).
- Lite, Jordan. December 11, 2008. "Diabetes and celiac disease: A genetic connection." Scientific American (SciAm.com).
- Naluai, A. T., et al. October 2000. "The CTLA4/CD28 gene region on chromosome 2q33 confers susceptibility to celiac disease in a way possibly distinct from that of type 1 diabetes and other chronic inflammatory disorders." Tissue Antigens 56:4 (350-355).
- Smyth, Deborah J., et al. December 10, 2008. "Shared and Distinct Genetic Variants in Type 1 Diabetes and Celiac Disease." NEJM 359:26 (2767-2677).